<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="../css/reset.css">
    <style>
        .a {
            width: 1200px;
            height: 58px;
            background-color: #f00;

            /* 溢出隐藏 */
            overflow: hidden;
        }

        .a1 {
            width: 200px;
            height: 50px;
            margin: 8px;
            float: left;
        }

        .b {
            width: 1200px;
            height: 100px;
            background-color: #ddd;
        }
    </style>
</head>

<body>

    <div class="a">
        <div class="a1"></div>
    </div>

    <div class="b">
        <h3>case案例</h3>
    </div>

</body>

</html>